The present invention relates to a fluorine-containing polymer, a process for preparing the polymer, and the use of the polymer, for example, in a stainproof substrate having a stainproof layer of said polymer on a surface thereof.
Materials such as metals, glass and resins are used as general-purpose substrates for a variety of articles such as automotive parts, OA apparatus and home electric appliances. The surfaces of these substrates are liable to get stained by the adhesion of dust particles suspended in the atmosphere of car interior, office interior, room interior and the like, and by the adhesion of oily substances which are contained in foods, oils for machines and the like and are difficult to be wiped off, and also by the adhesion of fingerprints of users. Therefore, these substrates need to be subjected to a stainproof treatment so that the substrate surface is rendered less adherent to dirt and the dirt once adhered can be easily removed.
As to the stainproof treatment of glass surface, publications such as Japanese Patent Application Laid-Open No. 126244/1989 (JP-A-1-126244) disclose techniques wherein coating films are formed either by direct application of a polymeric substance such as a polydimethylsiloxane to the glass surface or by immersion of glass in a treatment agent containing such a polymeric substance. Also known is a technique wherein a chemical absorption fluorine-containing monomolecular film is formed on the glass surface (see JP-A-4-132637, etc.).
As to the stainproof treatment of metal surface, Japanese Patent Kokoku Publication No. 53913/1995 (JP-B-7-53913) discloses a technique relating to an organic composite-plated steel plate by the steps of forming a chromate coating containing a silica sol silane coupling agent on a galvanized steel and thereafter forming a thin layer with an isocyanate-based paint composition.
However, the above-described treatments of prior arts do not provide a sufficient stainproof against oily dirt. In addition, the prior art treatments are associated with the problem that fingerprints tend to adhere to the substrate surface which is touched with fingers and the removal therefrom of the fingerprints is difficult.
A first object of the present invention is to provide a fluorine-containing polymer which can form on a substrate a stainproof layer exhibiting an excellent stainproof property against oily dirt, particularly fingerprints, as well as a process for preparing the polymer.
A second object of the present invention is to provide a stainproof substrate which exhibits an excellent stainproof property against oily dirt, particularly against fingerprints, as well as a process for preparing the substrate.
According to the present invention, the first object can be achieved by a fluorine-containing polymer having a number-average molecular weight of 500 to 100,000 and represented by the following general formula (I):
Rfxe2x80x94(OC3F6)axe2x80x94(OC2F4)bxe2x80x94(OCF2)cxe2x80x94Xxe2x80x94Yxe2x80x94Zxe2x80x94MPnRmxe2x88x92nxe2x80x83xe2x80x83(I)
wherein
Rf is a perfluroalkyl group;
a, b and c independently represent 0 or a number equal to or greater than 1, with the proviso that the sum of a, b and c is at least 1;
X is a group represented by the formula: xe2x80x94(O)dxe2x80x94(CF2)exe2x80x94(CH2)fxe2x80x94(where d, e and f independently represent 0 or a number equal to or greater than 1, with the proviso that the sum of e and f is at least 1, and the presence order of the bracketed repeating units is arbitrary in the formula);
Y is a divalent polar group;
Z is a group represented by the formula: xe2x80x94(CH2)gxe2x80x94(where g is 0 or a number equal to or greater than 1);
M is a metal atom;
R is a hydrocarbon group;
P is a hydrolyzable polar group;
m is an integer equal to xe2x80x9c(valency of M)xe2x88x921xe2x80x9d,
n is an integer of 1 to m;
with the proviso that the presence order of the bracketed repeating units is arbitrary in the formula; xe2x80x94OC3F6xe2x80x94 represents either xe2x80x94OCF2CF2CF2xe2x80x94 or xe2x80x94OCF(CF3)CF2xe2x80x94; and xe2x80x94OC2F4xe2x80x94 represents either xe2x80x94OCF2CF2xe2x80x94 or xe2x80x94OCF(CF3)xe2x80x94.
A preferred example of the fluorine-containing polymer (I) is a fluorine-containing polymer having a number-average molecular weight of 500 to 100,000 and represented by the following general formula (III):
Rfxe2x80x94(OCF2CF2CF2)axe2x80x94Xxe2x80x94Yxe2x80x94Zxe2x80x94SiPnR3xe2x88x92nxe2x80x83xe2x80x83(III)
wherein Rf, X, Y, Z, P and R are the same as defined above, and n is an integer of 1 to 3, with the proviso that a is a number equal to or greater than 1.
Likewise, the first object can be achieved by a fluorine-containing polymer having a number-average molecular weight of 500 to 100,000 and represented by the following general formula (II):
xe2x80x83PnRmxe2x88x92nMxe2x80x94Zxe2x80x94Yxe2x80x94Xxe2x80x94(OC3F6)axe2x80x94(OC2F4)bxe2x80x94(OCF2)cxe2x80x94Xxe2x80x94Yxe2x80x94Zxe2x80x94MPnRmxe2x88x92nxe2x80x83xe2x80x83(II)
wherein X, Y, Z, M, P, R, a, b, c, m and n are the same as defined above.
In the general formulae (I) and (III), Rf may be any perfluoroalkyl group contained in known fluorine-containing organic polymers, and may be, for example, a linear or branched perfluoroalkyl group having 1 to 16 carbon atoms. Preferably, Rf is CF3xe2x80x94, C2F5xe2x80x94 or C3F7xe2x80x94.
In the general formulae (I) and (II), a, b and c represent, respectively, the numbers of the three-type repeating units in the perfluoropolyethers constituting the main skeleton of the fluorine-containing polymer, wherein a, b and c are each 0 or a positive number equal to or greater than 1, with the proviso that a+b+c is at least 1. Preferably, a, b and c are independently selected from 0 and a number in the range of from 1 to 200. More preferably, a, b and c are each 1 to 100 when the number-average molecular weight of the fluorine-containing polymer is taken into consideration.
The presence orders of the repeating units in brackets having subscripts a, b and c are described according to specific presence orders in the general formulae (I) and (II) for the purpose of convenience. However, the linkage orders of these repeating units are arbitrary without being limited by these orders.
In the general formulae (I), (II) and (III), X is a group represented by the formula: xe2x80x94(O)dxe2x80x94(CF2)exe2x80x94(CH2)fxe2x80x94. In this formula, d, e and f independently represent 0 or a positive number equal to or greater than 1 (e.g., 1 to 50), with the proviso that e+f is at least 1, and the presence order of the repeating units in brackets having subscripts d, e and f is not limited in the formula. Preferably, d, e and f are each 0, 1 or 2. More preferably, d is 0 or 1, e is 2, and f is 0 or 1.
In the general formulae (I), (II) and (III), Y is a divalent polar group. Examples of the divalent polar group may include xe2x80x94COOxe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94NHCOxe2x80x94, xe2x80x94OCH2CH(OH)CH2xe2x80x94, xe2x80x94CH2CH(OH)CH2Oxe2x80x94 xe2x80x94COSxe2x80x94, xe2x80x94SCOxe2x80x94 and xe2x80x94Oxe2x80x94. Preferably, Y is xe2x80x94COOxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94OCH2CH(OH)CH2xe2x80x94 or xe2x80x94CH2CH(OH)CH2Oxe2x80x94.
In the general formulae (I), (II) and (III), Z is a group represented by the formula: xe2x80x94(CH2)gxe2x80x94. In this formula, g represents 0 or a positive number equal to or greater than 1 (e.g., 1 to 50). Preferably, g is 0, 1, 2 or 3.
In the general formulae (I), (II) and (III), M is a metal atom. Examples of the metal atom may include metallic elements which constitute Groups 1 to 15 (e.g., Si, Al and Ti) of the Periodic Table.
In the general formulae (I) and (II), m is equal to xe2x80x9c(valency of M)xe2x88x921xe2x80x9d and 0 or a positive number, while n is an integer of 1 to m. The valency of M is ordinarily 1 to 5, for example, 2 to 5, and particularly 3 to 5.
In the general formula (III), n is an integer of 1 to 3.
For example, in the case where M is silicon (Si), m is 3, and n is 1, 2 or 3. Meanwhile, in some cases, the fluorine-containing polymer is present as a mixture of polymers which are represented by the general formula (I), (II) or (III) and have different values for n. If the fluorine-containing polymer is present as a mixture of polymers as described above, n can be given as an average in the mixture.
In the general formulae (I), (II) and (III), the hydrocarbon group represented by R is preferably a hydrocarbon group containing 1 to 5 carbon atoms. Specific examples of the hydrocarbon group may include alkyl groups such as xe2x80x94CH3, xe2x80x94C2H5 and xe2x80x94C3H7.
Examples of the hydrolyzable polar group represented by P may include halogen, xe2x80x94OA, xe2x80x94OCOA, xe2x80x94Oxe2x80x94Nxe2x95x90C(A)2 (where A is an alkyl group such as xe2x80x94CH3, xe2x80x94C2H5 and xe2x80x94C3H7).
The number-average molecular weight of the fluorine-containing polymer is ordinarily 500 to 100,000. If the number-average molecular weight is less than 500, the polymer is useless because good properties of a polymer are not exhibited. On the other hand, if the number-average molecular weight is more than 100,000, the processability of the polymer is impaired. Preferably, the number-average molecular weight is 1,000 to 10,000.
The polymer (I) can be prepared by the reaction preferably between a compound represented by the following general formula (IV):
Qxe2x80x94Zxe2x80x94Mxe2x80x94PnRmxe2x88x92nxe2x80x83xe2x80x83(IV)
wherein Z, M, P, R, m and n are the same as defined above, and Q is a polar group, and either a compound represented by the following general formula (V):
Rfxe2x80x94OC3F6)axe2x80x94(OC2F4)bxe2x80x94(OCF2)cxe2x80x94Xxe2x80x94Txe2x80x83xe2x80x83(V)
wherein Rf, X, a, b and c are the same as defined above, and T is a polar group, or a compound represented by the following general formula (VIII):
Rfxe2x80x94(OCF2CF2CF2)axe2x80x94Xxe2x80x94Txe2x80x83xe2x80x83(VIII)
wherein Rf, X and a are the same as defined above, and T is a polar group.
Further, the polymer (II) can be synthesized by the reaction preferably between a compound represented by the following general formula (IV):
Qxe2x80x94Zxe2x80x94Mxe2x80x94PnRmxe2x88x92nxe2x80x83xe2x80x83(IV)
wherein Z, M, P, R, m and n are the same as defined above, and Q is a polar group, and a compound represented by the following general formula (VI):
Txe2x80x94Xxe2x80x94(OC3F6)axe2x80x94(OC2F4)bxe2x80x94(OCF2)cxe2x80x94Xxe2x80x94Txe2x80x83xe2x80x83(VI)
wherein X, a, b and c are the same as defined above, and T is a polar group.
Furthermore, the polymer (III) can be prepared by the reaction preferably between a compound represented by the following general formula (VII):
xe2x80x83Qxe2x80x94Zxe2x80x94SiPnR3xe2x88x92nxe2x80x83xe2x80x83(VII)
wherein Z, P and R are the same as defined above, n is an integer of 1 to 3, and Q is a polar group, and a compound represented by the following general formula (VIII):
Rfxe2x80x94(OCF2CF2CF2)axe2x80x94Xxe2x80x94Txe2x80x83xe2x80x83(VIII)
wherein Rf, X and a are the same as defined above, and T is a polar group.
Examples of the polar group represented by Q may include xe2x80x94OH, xe2x80x94NH2, xe2x80x94SH, 
xe2x80x94Hal (halogen) and xe2x80x94COOH.
Examples of the polar group represented by T may include xe2x80x94OH, xe2x80x94COOH, xe2x80x94NH2, 
and xe2x80x94COxe2x80x94Hal (acid halide).
The second object of the present invention can be achieved by a stainproof substrate comprising a substrate, and a layer of the fluorine-containing polymer presented by the general formula (I), (II) or (III) on the substrate.
The polymer layer can be formed by applying a separately prepared polymer (I), (II) or (III) to the substrate surface. On the other hand, in a preferred embodiment, the polymer layer (I), (II) or (III) can be formed by a process comprising forming on the substrate surface a layer of a compound represented by the general formula (IV) and reacting therewith a compound represented by the general formula (V) or (VI) or alternatively by a process comprising forming on the substrate surface a layer of a compound presented by the general formula (VII) and reacting therewith a compound represented by the general formula (VIII).
In the case where a layer of the fluorine-containing polymer is formed by a coating method, a solution, suspension liquid or dispersion liquid of the fluorine-containing polymer is coated on the substrate surface, and then is dried. The coating method may be a conventionally known one and examples of the coating method may include spraying, spin coating, immersion, roll coating, gravure coating and curtain flow coating.
A solvent in which the polymer is dissolved, suspended or dispersed is not particularly limited. Preferred examples of the solvent may include perfluorohexane, perfluoro-1,3-dimethylcyclohexane and dichloropentafluoropropane (HCFC-225).
In the case where a layer of the fluorine-containing polymer is formed by successively applying a compound (IV) and a compound (V) to the substrate surface and reacting the two compounds, and examples of the method for coating the compounds (IV) and (V) may include spraying, spin coating, immersion, roll coating, gravure coating and curtain flow coating.
When applying the compounds (IV) and (V), these compounds are preferably dissolved, suspended or dispersed in a solvent. The solvent is not particularly limited. For example, in the case of the compound (IV), conventionally used organic solvents, such as acetone, methyl isobutyl ketone and ethanol, can be used, while, in the case of the compound (V), useful solvents include perfluorohexane, perfluoro-1,3-dimethylcyclohexane and dichloropentafluoropropane (HCFC-225).
Although the thickness of the fluorine-containing polymer layer in the stainproof substrate of the present invention is not limited, the thickness is preferably 0.001 xcexcm to 0.03 xcexcm.
The types of the substrate to be stainproof in the present invention are not particularly limited. Accordingly, examples of the substrate may include glass, resins, metals, ceramics, wood, porcelain, stone and leather.
As to the glass substrates, the substrates are not particularly limited so long as they are made from glass. Examples of the substrate may include glass for use on the surface of a variety of articles such as show windows, mirrors, water baths, windowpanes, tablewares and glass cases.
As to the resin substrates, the substrates are not particularly limited and examples thereof include articles made not only from natural resins but also from synthetic resins.
Examples of the natural resins may include cellulose and japan lacquer. Examples of the synthetic resins may include polyamide resins, polyacrylate resins, polyamideimide resins, polyvinyl acetate resins, polyvinyl chloride resins, phenol resins, urea resins, melamine resins, epoxy resins and polyester resins.
Examples of the metal substrate may include iron, zinc, lead, copper and aluminum.
Meanwhile, the compound (VII) (silane coupling agent and the like), the compound (V) and the compound (VI) are all commercialized and are easily available.
For example, the following compounds are commercially available as the compound (VII) (silane coupling agent and the like) by Toray Dow Coring Co., Ltd.
On the other hand, the following compounds are commercially available as the compounds (V) and (VI).
C3F7xe2x80x94(OCF2CF2CF2)axe2x80x94OCF2CF2CH2OH
C3F7xe2x80x94(OCF2CF2CF2)axe2x80x94OCF2CF2COOH
C3F7xe2x80x94[OCF(CF3)CF2]aOCF(CF3)COOH
CF3xe2x80x94(OC3F6)axe2x80x94(OCF2)cxe2x80x94OCF2COOH
HOCH2CF2xe2x80x94(OCF2CF2)bxe2x80x94(OCF2)cxe2x80x94OCF2CH2OH
In addition, C3F7xe2x80x94(OC3F6)axe2x80x94OCF2CF2COF is available as one of raw materials for these compounds (JP-B No. Showa 63-43419 (43419/1988)). A compound such as C3F7xe2x80x94(OC3F6)axe2x80x94OCF2CF2CN can be derived therefrom (Ind. Eng. Chem. Res., 1987, 26, 1980). Reduction of the foregoing compound provides C3F7xe2x80x94(OC3F6)axe2x80x94OCF2CF2CH2NH2.
The reaction between C3F7xe2x80x94(OC3F6)axe2x80x94OC2F4CH2OH and epichlorohydrin provides 
The reaction between C3F7xe2x80x94(OC3F6)axe2x80x94OC2F4CH2H and a metal hydride MHx (M is a metal and x is a number of 1 to 6) (e.g., KH and NaH) provides C3F7xe2x80x94(OC3F6)axe2x80x94OC2F4CH2OM (metal alcoholate).
A fluorine-containing compound (I) or (II) terminated with a metal coupling group can be obtained by chemically combining the perfluoropolyether (V) or (VI) with the compound (VII) through the reaction between the polar groups thereof.
Examples of the reaction between the polar groups are given below.
In the following, for the purpose of simplification,
Rfxe2x80x94(OC3F6)axe2x80x94(OC2F4)bxe2x80x94(OCF2)cxe2x80x94Xxe2x80x94
and
xe2x80x83xe2x80x94Xxe2x80x94(OC3F6)axe2x80x94(OC2F4)bxe2x80x94(OCF2)cxe2x80x94Xxe2x80x94
in the general formulae (V) and (VI) are expressed as xe2x80x9cPFPExe2x80x9d. Likewise, Zxe2x80x94Mxe2x80x94PnRmxe2x88x92n in the general formula (IV) is expressed as xe2x80x9cMCxe2x80x9d.
Accordingly, the general formula (V) is expressed as xe2x80x9cPFPE-Txe2x80x9d, the general formula (VI) as xe2x80x9cT-PFPE-Txe2x80x9d, and the general formula (IV) as xe2x80x9cMC-Qxe2x80x9d. In this case, the general formula (I) is xe2x80x9cPFPE-Y-MCxe2x80x9d and the general formula (II) is xe2x80x9cMC-Y-PFPE-Y-MCxe2x80x9d.
If an ordinary polar group is selected as T and Q, the fluorine-containing polymers (I) and (II) can be obtained by, for example, the following reactions.
PFPExe2x80x94COOH+H2Nxe2x80x94MCxe2x86x92PFPExe2x80x94CONHxe2x80x94MC(+H2O)
xe2x80x83xe2x86x92MCxe2x80x94CH2CH(OH)CH2Oxe2x80x94PFPExe2x80x94OCH2CH(OH)CH2xe2x80x94MC
PFPExe2x80x94COOH+HSxe2x80x94MCxe2x86x92PFPExe2x80x94COSxe2x80x94MC(+H2O)
KOxe2x80x94PFPExe2x80x94OK+2Clxe2x80x94MCxe2x86x92MCxe2x80x94Oxe2x80x94PFPExe2x80x94Oxe2x80x94MC(+2KCl)
PFPExe2x80x94COF+HOxe2x80x94MCxe2x86x92PFPExe2x80x94COOxe2x80x94MC(+HF)
HOOCxe2x80x94PFPExe2x80x94COOH+2HOxe2x80x94MCxe2x86x92MCxe2x80x94OCOxe2x80x94PFPExe2x80x94COOxe2x80x94MC(+2H2O)
Since a metal coupling material is unstable to water, it is preferable that the coating film on the substrate surface is formed by a procedure in which a compound (IV) is first applied to the substrate surface and thereafter the compound (IV) is reacted with a compound (V) or (VI) if water is generated as a by-product.
The substrates whose surface is rendered stainproof according to the present invention can be used as parts of the following articles which are liable to be stained.
Home electric appliances such as blades of electric fans, doors of electronic ovens, and surface of electric refrigerators; office articles such as contact glass of copying machines, mirrors of OHP main bodies, OHP sheets, key boards, telephones and desks; home articles such as glass, doors of cupboards, mirrors, windowpanes, lampshades and chandeliers; architectural members such as show windows, telephone boxes and glass of water baths; automotive parts such as glass and paint films on bodies of vehicles; personal ornaments such as frames of a pair of spectacles, glass of underwater cameras, goggles, helmets and cover glass of dial plates of watches; play goods such as glass of pinball tables, trumps and mahjong tiles; and paint film surfaces of articles such as furniture and piano.
Ornament pieces such as necktie pins, necklaces and pierced earring; metal or plated articles such as faucets of water supply, metal wind instruments, wooden wind instruments, golf clubs, door handles, dumbbells and knifes; stone articles such as gravestones, go game stone pieces and marbles; paper products such as wall paper, paper for sliding partitions, books, posters and photographs; and leather products such as wallets, shoes, bags, wrist watch bands and baseball gloves.